Gata Kamsky is the reigning US champion. He came within one match of playing for the world championship in 2010. And he’s the only American with a shot at the 2012 world championship match.

So why is he considered only No. 2 in America? The reason is ratings. Hikaru Nakamura’s recent results moved him into the top spot, and that’s what counts according to fans.

Before the Elo rating system won acceptance 40 years ago, it was impossible to tell when a changing of the guard occurred. For example, Frank Marshall was US champion from 1909 to 1936. But that’s misleading.

Retro-ratings compiled by chessmetrics.com show that Marshall became the top American in 1905 and remained so until 1930, when he was supplanted by Isaac Kashdan. Yet “Kash” is largely forgotten today because there were no ratings and he never challenged Marshall in a match.

By late 1936, when US championship tournaments began, Kashdan had been surpassed by Sammy Reshevsky. Except for a brief period in the late 1930s, Reshevsky reigned as the strongest American until he was dethroned by Bobby Fischer in mid-1959.